Since Kodachrome was put on sale by Eastman Kodak Co. in 1935, various improvements in color photography have been continueing and enhancement of its photographic performance is still in advance, including fine image structure, enhancement of graininess and, and enhanced color reproducibility. Of these, with regard to a technique for enhancing color reproduction, there was some marked enhancement of color reproduction so far. One of them concerns a colored coupler having an automasking function (as described in U.S. Pat. No. 2,455,170).
The colored coupler is mainly used for enhancing color reproduction of a color negative film. The colored coupler contributes to correct unwanted absorption of yellow, magenta and cyan dyes used in the color negative film. Thus the colored coupler compensates for imagewise color contamination due to unwanted absorption of the dye, leading to greatly enhanced color reproduction.
Clearer color reproduction is also desired and as a technique for enhancing color purity of the color negative film, there was proposed a development effect, so-called interlayer effect described in Belgian Patent 710,344 and German Patent 2,043,934.
Furthermore, to promote the interlayer effect, a DIR coupler was developed, as described in U.S. Pat. No. 3,277,554, leading to marked enhancement in color purity reproduction.
Thus enhanced chromatic color reproduction is aimed, while there was proposed techniques to faithfully reproduce color as seen by the human eye. One of them concerns control of spectral sensitivity distribution of a blue-sensitive layer, a green-sensitive layer and a red-sensitive layer of a color film, as described in JP-A 5-150411 (hereinafter, the term, JP-A means a unexamined, published Japanese Patent Application).
There were further proposed techniques of enhancing color reproduction, in which differences in spectral sensitivity distribution between cones of the human eye and the color film was noted. The color film generally has a spectral sensitivity distribution such that a blue-sensitive layer has a sensitivity maximum at longer wavelengths, a green-sensitive layer has a sensitivity maxim at slightly longer wavelengths and a red-sensitive layer has a sensitivity maximum at rather longer wavelengths, as compared to the spectral sensitivity distribution of the human eye. Further, red cones of the eye have a region in the vicinity of 500 nm, having negative sensitivity. To allow the spectral sensitivity of the color film to meet the spectral sensitivity of the eye, the spectral sensitivity distribution by use of sensitizing dyes and the interlayer effect by use of a so-called donor layer were controlled, enabling faithful reproduction, to a certain extent, of intermediate colors, which had been hard to reproduce, as described in JP-A 61-34541.
Employing these techniques, color reproducibility of the color film enabled hue of objects to be faithfully reproduced.
As mentioned above, color reproducibility of color photography has steadily been advanced. However, it is still true that with regard to the color photographic materials of the next generation, further enhancement of color reproducibility having different aspects is still desired. The reason for this is that amateur photographers are often still disappointed when they receive their prints. Cited as disappointments are often, when photographing fresh green woods, red flowers and distant mountain ranges. There are numerous photographers, when they have taken such pictures and receive the processed prints, the resulting prints are different from their expectation or from what they had in mind, in which the fresh green color of woods shows dark and dull tones, the fine details of petals of the red flowers is lost, leading to so-called red saturation, and the distant mountain ranges appear to be veiled in mist, losing the three dimensional realism in which they were originally viewed.
Thus color photography is not satisfactory simply with faithfulness and clearness in color reproduction but it also requires excellent image rendering, which vividly reproduce the scene being photographed.
On the other hand, along with recent progress of information processing technology, development of a technique is being advanced, in which images of a color negative film or a color reversal film can be read with a color scanner to be converted to digital image signals, which are further subjected to an appropriate image processing, and thereafter, output signals are produced in response to these image information and recorded on an outputting material such as color print paper.
In fact, the use of the technique of temporarily converting to digital images make it easy to make correction so as to form the images expected by the user. However, a limitation still remains in that it is impossible to exceed the amount of information recorded on the color film.
Herein, there still remain problems to be solved with regard to how to record subject information at the time of photographing as many as possible on the color film and apply them in the process of digital image processing to satisfy requirement of clearly reproduce the scene at the time of user's photographing. In this regard, the method thereof has not yet been established.